Recently, what is known as multimode imaging, combining acquisition of various types of image, has experienced considerable growth in the medical diagnostic field. This is because it makes it possible to obtain both morphological and functional information. The first are obtained using X-ray or ultrasound probes and the second using positron emission tomography (PET) or magnetic resonance imaging (MRI) or using fluorescence imaging. In particular, the pairing of ultrasound/optical techniques seems particularly pertinent to certain applications such as mammography or the detection of anomalies in the prostate because these techniques are compatible in terms of cost, compactness and penetration depth.
Many research teams are currently developing instruments based on these two imaging modes, either for diagnostic applications or for phototherapy treatment applications.
At the present time, the main diagnostic tool for prostate cancer consists in carrying out several biopsies guided by and using an endorectal ultrasound probe. For the examination, the practitioner slips a sterile protective membrane around the probe reducing the risk of nosocomial infections. This protective membrane may be, depending on the practitioner, a simple condom or even a dedicated sterile glove. In France, each hospital follows its own procedure for sterilizing these probes.
However, during the ultrasound-guided biopsy protocol, the risk of the sterile protective membrane being perforated is about 9%. It is not negligible and leads to a risk of infection. The reader is referred to the study by J. Masood, S. Voulgaris, O. Awogu, C. Younis, A. J. Ball and T. W. Carr, “Condom perforation during transrectal ultrasound guided (TRUS) prostate biopsies: a potential infection risk,” International Urology and Nephrology, Vol 39, 2007, p 1121-1124 for more information on this problem.
Furthermore, existing sterile gloves are not designed to be compatible with fluorescence measurements. In particular the following problems arise:                dyes present in the material from which the protective membranes are made absorb some of the absorption and excitation light;        the material from which the protective membrane is made may also induce a parasitic fluorescence signal in the wavelength range used; and        the protective membrane may also, under certain conditions, deteriorate under the effect of laser light. Mention may be made, for example, of photoablation methods, which use a high-power laser to cut tissue.        
Moreover, for several years sterilization criteria for tools used in medical environments have become more and more rigorous, thereby resulting in a tendency to use thicker, and therefore more light-absorbent, sterile gloves.
It is accepted at the present time that it is advantageous to use a probe which makes it possible to carry out both echography and fluorescence imaging, and some have chosen to develop dedicated devices, integrating an optical mode and acoustic echography in one and the same probe. Adding the optical mode is however liable to degrade the seal of the ultrasound part of the probe. This is because the presence of optical fibres protruding slightly from the surface of the probe may cause breaks in the seal of the whole device. Moreover, including optical fibres in an ultrasound probe represents a real technical challenge because these fibres have already been optimized for bulk. Such a modification implies completely reviewing current probe design and replacing existing probes, something that practitioners are loathe to do.
To solve the problems posed both by the dual-modality and sterilization of the probe, several solutions have been provided.
An American team proposed an ultrasonically and optically coupled probe for diagnosis of prostate cancer. The team was Z. Jiang, G. Holyoak, K. Bartels, J. Ritchey, G. Xu, C. Bunting, G. Slobodov and D. Piao, “In vivo trans-rectal ultrasound-coupled optical tomography of a transmissible venereal tumor model in the canine pelvic canal,” JOURNAL OF BIOMEDICAL OPTICS, Vol 14, May 2009. However, this probe did not solve the problem of sterilization after use.
U.S. Pat. No. 5,283,722 of K. M. Peter and R. Trow, “Surgical-Type Glove and Illuminator Assembly” provided a sterile glove intended for a surgeon and equipped with a light source for illuminating the area of surgical work.
Another team proposed a fibre-coupled optical probe part of which was disposable, this probe was intended to measure certain properties of the blood, such as the pH, through a catheter. The reader is referred to the publication by W. W. Miller, M. Yafuso, C. F. Yan, H. K. Hui and S. Arick entitled “Performance of an in-vivo continuous blood-gas monitor with disposable probe” Clinical Chemistry, Vol 33, 1987, p 1538.
U.S. Pat. No. 4,870,952 of M. Martinez entitled “Fiber Optic Illuminator for Use in Surgery” describes a partially disposable optical probe for surgical applications.
It will also be noted that a Dutch team have proposed a disposable biopsy syringe for examining the prostate. The reader is referred to the publication by C. C. Schulman entitled “Transrectal prostatic biopsy” International Urology and Nephrology, Vol 2, 1970, p 157-161 on this subject.